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排序方式： 共有1393条查询结果，搜索用时 15 毫秒
161.
Madhesh Raji;Sreeja Balakrishnapillai Suseela;Srinivasan Manikkam;Gowthami Anbazhagan;Kentaro Kutsukake;Keerthivasan Thamotharan;Ramadoss Rajavel;Noritaka Usami;Ramasamy Perumalsamy; 《Asian Politics & Policy》2024,59(4):2300279
This paper provides a method for improving the photovoltaic conversion efficiency and optical attributes of silicon solar cells manufactured from as-cut boron doped p-type multi-crystalline silicon wafers using acid-based chemical texturization via machine learning. A decreased reflectance, which can be attained by the right chemical etching conditions, is one of the key elements for raising solar cell efficiency. In this work, the mc-Silicon wafer surface reflectance is obtained under (<2%) after optimization of wet chemical etching. The HF + HNO3 + CH3COOH chemical etchant is used in the ratio 1:3:2 at different conditions of the etching duration of 1 min, 2 min, 3 min, and 4 min, respectively. The as-cut boron doped p-type mc-silicon wafers are analysed with ultraviolet–visible spectroscopy, optical microscopy, Fourier transforms infrared spectroscopy, thickness profilometer, and scanning electron microscopy before and after etching. The chemical etching solution produces good results in 3 min etched wafer, with a reflectivity value of <2%.The reflectivity and optical images are inputs to the convolutional neural network model and the linear regression model to obtain the etching rate for better reflectivity. The classification model provides 99.6% accuracy and the regression model results in the minimum mean squared error (MSE) of 0.062. 相似文献
162.
Li Dai;Lin Zhang;Houliang Wang;Ning Lai; 《Asian Politics & Policy》2024,59(6):2300255
In this paper, Zr:Dy:LiNbO3 crystals are prepared by traditional pull-up method, in which Zr4+ doping concentrations are 0, 1, 2, and 4 mol%, respectively. In this paper, the defective structure of Zr:Dy:LiNbO3 crystals and their resistance to photodamage under different Zr4+ concentration doping are studied. Firstly, the influence of Zr4+ doping concentration on the defective structure of Zr:Dy:LiNbO3 crystal and the occupancy of doped ions under different Zr4+ concentrations are tested and discussed by infrared (IR) absorption spectroscopy and ultraviolet-visible near-infrared (UV–vis–NIR) absorption spectroscopy. The Judd–Ofelt theoretical analysis results show that when the concentration of doped Zr4+ is 2 mol%, the spectral quality factor (X) of Dy3+ in lithium niobate crystals is significantly improved compared with that of Dy3+ in other crystals. Secondly, resistance to photodamage of Zr:Dy:LiNbO3 crystals is studied and analyzed by the light scattering exposure energy flow threshold method. The results show that when the concentration of doped Zr4+ ions reaches 4 mol%, the exposure energy value is increased by 210 times compared with the no doping, which greatly improves the anti-photodamage performance of the crystal. 相似文献
163.
Kowsalya Murugan;Srinivasan Karuppannan; 《Asian Politics & Policy》2024,59(4):2300327
L-Menthol is a commonly used material in food production for flavor enhancement and fragrances, as well as in pharmaceuticals. However, during the solution crystallization process of L-menthol, there is a major issue of oiling out or liquid–liquid phase separation (LLPS) in most organic solvents and their mixtures. The objective of the current work is to prevent the LLPS phenomenon and grow high-quality single crystals of L-menthol. A water–ethanol mixed solvent with nine different mixing ratios is used, ranging from 0.99W:0.01E to 0.91W:0.09E, through the conventional slow evaporation process. The findings indicate that the mixing composition of the solvent plays a significant role in the variation of solubility, refractive index, LLPS, nucleation, and crystallization. This is clearly demonstrated in the phase diagram. The occurrence of LLPS phenomenon, nucleation, growth behavior, and morphology of L-menthol single crystals through optical microscopy is identified. Additionally, the internal structure and thermal stability of the grown polymorphs using PXRD, SCXRD, and DSC analyses are confirmed. 相似文献
164.
Shisi Tian MSc Yanyan Wang PhD Shuo Liu MSc Zhaolun Liu MSc Ya-Bin Zhao PhD 《Journal of forensic sciences》2024,69(2):448-460
The analysis of fingerprint chemical composition is a meaningful way to excavate the multidimensional information of fingerprint, including the donor profiling information and the age of a fingerprint, which broadens the evidential values of fingerprint, especially for the partial and distorted fingerprint. But the research remains still in the pilot phases or is ongoing. Amino acids are the dominant organic substances in latent sweat fingerprint and influenced by many donor factors. Hence, their content reflects personal information of donors. Forensic science will be revolutionized if suspects can be individualized by their amino acid content. The diverse nature, distinct physicochemical properties, and ultra-micro levels of amino acids present in fingerprints make it hard to detect. A high sensitivity method for detecting and quantifying multiple amino acid components is required. UHPLC-QqQ MS/MS offers high sensitivity, high separation, simultaneous multicomponents detection, and no derivatization, making it an ideal method for detecting and analyzing amino acids in fingerprints. Therefore, in this study, we propose and validate an efficient UHPLC-QqQ MS/MS method for the extraction and analysis of 13 amino acids from fingerprint. We compared the results of amino acids of 10 different substrates and found that the inherent amino acids in most porous substrates would have been extracted along with the fingerprint amino acids, making them unsuitable for quantitative amino acid analysis. Instead, plastic sheets are ideal substrates for laboratory studies. Then, extensive experiments were conducted among 30 donors for multidimensional information analysis. The type of samples analyzed were eccrine-rich fingerprints. A Binary Logistic Regression (BLR) model was developed, and the female and male donors were successfully differentiated by amino acids in fingerprints. Two other mathematical models were also developed to verify the accuracy, and all three different mathematical models were able to identify donors of different genders with over 90% accuracy. This demonstrates that amino acids have the potential to provide more information for donors as metabolic markers. In the future, we will conduct a series of experiments to analyze more multidimensional information for individual identification by amino acid content in the fingerprint. 相似文献
165.
Charley K. Mitchell;Jonathan C. Dumke;Charlotte A. Corbett;Laura M. Jones;Kristin E. Ceniccola-Campos; 《Journal of forensic sciences》2024,69(6):2222-2229
In the United States, illicit fentanyl is often trafficked as blue tablets mimicking the legitimate M-30 oxycodone tablet produced by Mallinckrodt. The analysis of dyes extracted from seized fentanyl tablets could provide a useful tool for law enforcement to establish linkages between cases and could prove useful for attributing a seizure to a given trafficking organization. Fentanyl tablet seizures associated with a particular drug trafficking organization (DTO), either through investigative or intelligence information, were used as the sample set for this study. The blue dye from the tablets was isolated by solid phase extraction and then qualitatively and quantitatively analyzed via ultraviolet-visible spectroscopy. This research revealed that the illicit tableting facilities use a different dye than several known pharmaceutical companies. The concentration of dye in individual tablets within a seizure proved to be very minimal, and the small sample size made it difficult to draw linkages from case to case. Analysis of the dyes could not effectively differentiate between the drug trafficking organizations in the tested population due to each DTO using the same dye; however, it is important to note that the dye found was consistent between illicit tablets. 相似文献
166.
Lyn R. Greenberg Kathleen McNamara Betsy E. Weisz Justice Thomas Altobelli Frank Davis 《Family Court Review》2023,61(3):522-537
Children and adolescents who are having difficulty coping with stress often present with complaints of physical discomfort. Effective treatment approaches exist for many of these issues. Among high-conflict parents, however, children's medical issues can become another canvas for conflict, with parents focused more on blaming one another for the child's distress than on options for assisting the child. Professionals can be drawn into the conflict to such a degree that they overlook essential steps for addressing and managing these issues. The authors present a research-informed model for managing medical and psychophysiological issues amid parental conflict. 相似文献
167.
Christopher J. Katilie BS Lauryn E. DeGreeff PhD Caitlin E. Sharpes MS Eric M. Best PhD Patricia E. Buckley PhD Jenna D. Gadberry BS Michele N. Maughan PhD 《Journal of forensic sciences》2023,68(6):2021-2036
While canines are most commonly trained to detect traditional explosives, such as nitroaromatics and smokeless powders, homemade explosives (HMEs), such as fuel–oxidizer mixtures, are arguably a greater threat. As such, it is imperative that canines are sufficiently trained in the detection of such HMEs. The training aid delivery device (TADD) is a primary containment device that has been used to house HMEs and HME components for canine detection training purposes. This research assesses the odor release from HME components, ammonium nitrate (AN), urea nitrate (UN), and potassium chlorate (PC), housed in TADDs. Canine odor recognition tests (ORTs) were used with analytical data to determine the detectability of TADDs containing AN, UN, or PC. Headspace analysis by gas chromatography/mass spectrometry (GC/MS) with solid-phase microextraction (SPME) or online cryotrapping were used to measure ammonia or chlorine, as well as other unwanted odorants, emanating from bulk AN, UN, and PC in TADDs over 28 weeks. The analytical data showed variation in the amount of ammonia and chlorine over time, with ammonia from AN and UN decreasing slowly over time and the abundance of chlorine from PC TADDs dependent on the frequency of exposure to ambient air. Even with these variations in odor abundance, canines previously trained to detect bulk explosive HME components were able to detect all three targets in glass and plastic TADDs for at least 18 months after loading. Detection proficiency ranged from 64% to 100% and was not found to be dependent on either age of material. 相似文献
168.
Kymeri Davis MS Madison Reavis MS John V. Goodpaster PhD 《Journal of forensic sciences》2023,68(3):815-827
The storage and use of explosives is regulated at the state and federal level, with a particular focus on physical security and rigorous accounting of the explosive inventory. For those working with explosives for the training and testing of explosive-detecting canines, cross-contamination is an important concern. Hence, explosives intended for use with canine teams must be placed into secondary storage containers that are new, clean, and airtight. A variety of containers meet these requirements and include screw-top glass jars (e.g., mason jars). However, an additional need from the explosive-detecting canine community is secondary containers that can also be used as training aids whereby the volatiles emitted by explosives are emitted in a predictable and stable manner. Currently, a generally accepted method for the storage of explosives and controlled emission of explosive vapor for canine detection does not exist. Ideally, such containers should allow odor to escape from the training aid but block external contaminates such as particulates or other volatiles. One method in use places the explosive inside a permeable cotton bag when in use for training and then stores the cotton bag inside an impermeable nylon bag for long-term storage. This paper describes the testing of an odor permeable membrane device (OPMD) as a new way to store and deploy training aids. We measured the evaporation rate and flux of various liquid explosives and volatile compounds that have been identified in the headspace of actual explosives. OPMDs were used in addition to traditional storage containers to monitor the contamination and degradation of 14 explosives used as canine training aids. Explosives were stored individually using traditional storage bags or inside an OPMD at two locations, one of which actively used the training aids. Samples from each storage type at both locations were collected at 0, 3, 6, and 9 months and analyzed using Fourier Transform Infrared (FTIR) Spectroscopy and Gas Chromatography–Mass Spectrometry (GC–MS) with Solid-Phase Microextraction (SPME). FTIR analyses showed no signs of degradation. GC–MS identified cross-contamination from ethylene glycol dinitrate (EGDN) and/or 2,3-dimethyl-2,3-dinitrobutane (DMNB) across almost all samples regardless of storage condition. The contamination was found to be higher among training aids that were stored in traditional ways and that were in active use by canine teams. 相似文献
169.
Timothy Yaroshuk MS Robert H. Powers PhD Alyssa L. M. Marsico PhD 《Journal of forensic sciences》2023,68(2):416-424
Human hairs are one of the most commonly encountered items of trace evidence. Currently, conventional methods for hair analysis include microscopic comparison and DNA analysis (nuclear and mitochondrial). Each approach has its own drawbacks. Hair proteins are stable and offer an alternative to DNA testing, as demonstrated with proteomics for distinguishing humans. However, proteomics is complicated and requires identifying peptides to remain intact following harsh sample preparation methods. Alternatively, the actual amino acid content of a hair sample may also offer important identifying information and actually requires proteins and peptides to be broken down completely rather than remaining intact. This study evaluated the discriminating power of using hair amino acid ratios to differentiate hair samples from 10 unrelated individuals with dark colored hair. Hair proteins were digested, derivatized, and analyzed using gas chromatography–mass spectrometry. Amino acid ratios were calculated for each individual and comparisons using ANOVA and post-hoc pairwise t-test with Bonferroni correction were made with amino acid ratios for individuals. Overall, out of the 45 possible pairwise comparisons between all hair samples, 38 (84%) were differentiable. Out of the 36 possible pairwise comparisons between brown haired individuals, 32 (89%) were considered differentiable using univariate statistics. Multivariate statistics were also attempted but, overall, univariate models were sufficient for exclusionary purposes. These results indicate that amino acid ratio analysis can potentially be used as an exclusionary method using hair if DNA analysis cannot be performed, or to corroborate conclusions made following microscopic analysis. 相似文献
170.
Biao Zhang 《Third world quarterly》2019,40(8):1459-1478
AbstractMost of the literature on state transformation focuses on China’s relations with African, Asian and Latin American countries and the National Oil Companies’ overseas expansion to show that China has become fragmented, decentralised and internationalised. This article contributes novel findings by focusing on China’s relations with Europe and the actions of China’s National Nuclear Companies (NNCs). It shows that NNCs, which have become relatively autonomous actors, often pursue their agendas of expansion into Europe without much coordination with, or even in contradiction to, other ministries’ agendas and interests, especially the Ministry of Foreign Affairs. Instead of being orchestrated by the central government, their expansion reflects considerable disorganisation and sometimes undermines China’s official strategy. The article demonstrates this through case studies of NNCs’ involvement in the UK and Romania. 相似文献